Preterm birth (PTB) occurs at unacceptably high rates within the United States (U.S.), with Black women disproportionally affected. To date, medical and public health interventions have achieved limited success in improving birth outcomes. Part of the problem could be that the efforts in the last several decades focused mainly on increasing access to prenatal care. The etiology of birth outcomes is complex, involving behavioral, psychosocial, socio-demographic, community, environmental, and medical factors. Psychosocial factors during pregnancy (e.g. stress, anxiety, depression, and coping responses) are gaining increased attention as critical contributing factors to poor birth outcomes. Interventions that do not address these broader factors in a comprehensive way may be less able to achieve success. Studies of CenteringPregnancy group prenatal care (GPNC), where individual physical assessments are combined with facilitated group education and peer support, have demonstrated promising results, including high rates of prenatal care use and care satisfaction, and improvements in PTB rates. Because GPNC provides social support and more time for visits, increasing patient education, skills for self-care, and empowerment, it holds great potential for improving birth outcomes and reducing racial disparities in birth outcomes. However, no study has yet conclusively determined the effects of GPNC on PTB in general, or the effect of this care model on racial disparities in PTB. Prior research has also not established GPNC effects on patient education, activation, and stress, which may influence birth outcomes as well as health behaviors and outcomes beyond the postpartum period. To fill this research gap, we propose to conduct a randomized controlled trial (RCT) to compare biomedical, behavioral and psychosocial outcomes by race among pregnant women who participate in GPNC, to women in the traditional individual prenatal care (IPNC) and to investigate whether improving women's stress, activation and engagement will explain the potential benefits of GPNC on outcomes and health disparities. The trial will be conducted in a large prenatal care center in South Carolina where the historical PTB rate has been as high as 16.4%. Eligible White and Black women will be recruited before 20 weeks of gestational age and will be followed to delivery and 6 weeks postpartum.